Measurement and correlation of isobaric vapour–liquid equilibrium for systems of o-cresol, m-cresol and 2, 6-dimethylphenol at 20.0 kPa

Isobaric vapour–liquid equilibrium (VLE) data for binary systems containing o-cresol (OC) + m-cresol (MC), OC + 2, 6-dimethylphenol (DMP), and MC + DMP at 20.0 kPa were measured by using a modified Othmer still. Its reliability was confirmed by measuring the saturated vapour pressure data for the components of MC and DMP. Herington area test was used to confirm the thermodynamic consistency for these binary systems, and the results showed good thermodynamic consistency. The binary VLE experimental data were correlated and predicted by Wilson, NRTL, and UNIFAC models. The results correlated by Wilson and NRTL models agree well with the experimental values. The results predicted by UNIFAC are in accordance with experimental data with rational deviations for systems OC + MC and OC + DMP but show relatively large deviations between the predicted values and experimental data for MC + DMP system. By defining the group =COH in DMP and MC as two different groups, the experimental data were correlated, and new groups with binary interaction parameters were obtained. The results calculated by UNIFAC with new defining groups are in accordance with the experimental data.